The proposed research is aimed at defining the roles played by antigen and antibody in the regulation of nucleic acid synthesis and proliferation of antibody-producing cells. It is expected that an understanding of the fundamental regulatory mechanisms involved in antibody formation will provide a basis for controlling immunological processes. It is hoped that through an understanding of the mechanisms involved in the homeostatic control of a model antibody-producing cell population, insight may be obtained into more general problems involving cell proliferation, differentiation, and regulation of these activities.